Sunday, August 31, 2014

Soggy end to wet but warm August..

It was a wet finish to the month of August over Winnipeg and the Red River valley as another weather system brought widespread rain to southern Manitoba today. In general about 15-25 mm of rain fell in most areas, with 20 to 40 mm over parts of the southern RRV and southwest MB. In Winnipeg, the official rainfall at the airport today was 18 mm, with 17 mm falling at the Forks. At my location in Charleswood, I picked up 21.6 mm today bringing my monthly total to 137 mm.. well above the August average of 77 mm. The bulk of this month's rain has fallen over the past 2 weeks, with a couple of significant rainfalls across the city including August 21st when a slow moving thunderstorm complex dumped 50-100 mm over the southwest to central parts of the city. Officially, the airport recorded 104 mm this month, while the Forks had 133 mm with amounts over 170 mm from the Tuxedo to Linden Woods area.

The wet finish to the month was in sharp contrast to a dry July and first half of August which saw below normal precipitation in Winnipeg. Temperature-wise, August will finish with an average temperature around 19.3C at YWG airport.. slightly above the average August temperature of 18.8C.

12 comments:

Having some issues with my main website not updating my weather station graphics. Stuck on 2:30 pm readings for some reason. Trying to fix the problem with no luck so far.. but just letting you know I'm aware of it..

Still can't figure out why my weather station info isn't updating properly. Appears that jpeg image files are not getting uploaded to Shaw server for some reason (began yesterday after 230 pm). Some are, but most aren't. Still trying to troubleshoot.. tried a few fixes but nothing working so far.

Complex scenario unfolding for the next few days. Upper flow will turn increasingly SW in response to a digging upper trough over BC. Lead shortwave ejects out and taps plains LLJ as early as Tuesday overnight with main focus to our southeast. At the surface, warm front starts taking shape and lifts to around international border during the day Wednesday.

Main upper trough then starts moving east and surface low starts closing off. LLJ retrogrades back to the west setting the stage for two main areas of precipitation by Wednesday evening.. 1) on the nose of the main axis of lower level moisture transport and 2) in the deformation zone of the upper trough with midlevel frontogenesis and trowal wrapping around the parent circulation.

NAM right now suggests Winnipeg will stay mainly in the dry slot of the system with low precipitation totals. However, if LLJ can phase better/sooner with the approaching trough, we would be in line for very strong moisture advection of PWATS over 50 mm (higher than with the past systems).

Crossing my fingers, but I think I solved the issue with my weather station not updating. Had to delete a corrupted file.. but I think we're back in business again, just as this line of thunderstorms rolls though. Unfortunately, I haven't been able to fix my wind direction sensor.. It moves, but display is stuck at a NW direction (320) Cable is likely frayed somewhere, but I haven't been able to find out where. As a result, my weather station will always be displaying a NW wind for the foreseeable future. Wind speed however is updating correctly.

Anon.. I think we're just having a prolonged storm season due to the abundant surface moisture still present, along with a favourable jet stream bringing systems in every few days. It's still warm enough for some decent instability to trigger these late season storms. As for tonight into tomorrow, we have another storm system tracking through the Dakotas spawning showers and thunderstorms, possibly severe near and south of the US border. Area of convection will morph into a swath of heavier rain north of the border as moisture streams north and spreads along deformation axis over southern Prairies. Latest model guidance showing swath of heaviest rain setting up from SE SK and SW MB into the Interlake where 25-50 mm is possible by tomorrow afternoon . Lesser amounts over RRV but local downpours likely with thunderstorms. I will try to post an update today on this system.

Lots of uncertainty regarding precipitation potential and evolution of system. Elevated convection right now down in central Minnesota associated with LLJ moving east - and showers associated with midlevel forcing from parent trough over SW Manitoba and southern RRV. Models struggling with phasing of energy as main upper trough and surface low consolidates overnight and track over SE Manitoba during the day tomorrow.

Models show modest linkage between the LLJ/low level moisture transport and the main trough overnight. A weak southeasterly LLJ forms, and that will be the main threat for elevated convection overnight, otherwise steadier rain should be focused to our NW. Models also disagree on the track of tomorrow's low, with NAM tracking the low nearly over Winnipeg (and giving us low twenties for afternoon temperatures). GFS is further east. Band of steadier rain and cold temperatures (mid to high single digits) slumps SE during the later afternoon hours..